https://www.gamespot.com/articles/xbox-one-x-significantly-improves-halo-5-guardians/1100-6454942/

Halo 5: Guardians was a marquee Xbox One game when it released back in 2015, but it has come back into the conversation as one of the platform's highlights with its Xbox One X enhancements. As they always do, Eurogamer's Digital Foundry did a full-fledged analysis on how the games runs, from its resolution and visual effects to how the framerate holds up.

The game uses dynamic resolution scaling to make sure it maintains a consistent, silky-smooth 60 frames per second. Unfortunately, this meant sub-1080p resolution (sometimes as low as 810p) on the original Xbox One during most scenarios. The result was an often blurry image that obscured the finer details in the game. However, the Xbox One X enhancement negates most of that compromise.